Donghu, Toba, and Rouruan
Although the Xiongnu finally had been driven back into their homeland by the Chinese in AD 48, within ten years the Xianbei (or Hsien-pei in Wade-Giles) had moved (apparently from the north or northwest) into the region vacated by the Xiongnu. The Xianbei were the northern branch of the Donghu (or Tung Hu, the Eastern Hu), a proto-Mongol and/or Tunguz group mentioned in Chinese histories as existing as early as the 4th century BC. The language of the Donghu, unlike that of the Xiongnu, is believed to be proto-Mongolic to modern scholars. The Donghu were among the first peoples conquered by the Xiongnu. Once the Xiongnu state weakened, however, the Donghu rebelled. By the 1st century AD, two major subdivisions of the Donghu had developed: the proto-Mongolic Xianbei in the north and the Wuhuan in the south. The Xianbei, who by the 2nd century AD were attacking Chinese farms south of the Great Wall, established an empire, which, although short-lived, gave rise to numerous tribal states along the Chinese frontier. Among these states was that of the Toba (T'o-pa in Wade-Giles), a subgroup of the Xianbei, in modern China's Shanxi Province. The Wuhuan also were prominent in the 2nd century, but they disappeared thereafter; possibly they were absorbed in the Xianbei western expansion. The Xianbei and the Wuhuan used mounted archers in warfare, and they had only temporary war leaders instead of hereditary chiefs. Agriculture, rather than full-scale nomadism, was the basis of their economy. In the 6th century, the Wuhuan were driven out of Inner Asia into the Russian steppe.
Chinese control of parts of Inner Asia did not last beyond the opening years of the 2nd century AD, and, as the Eastern Han Dynasty ended early in the 3rd century AD, suzerainty was limited primarily to the Gansu corridor. The Xianbei were able to make forays into a China beset with internal unrest and political disintegration. By 317 all of China north of the Yangtze River (Chang Jiang) had been overrun by nomadic peoples: the Xianbei from the north; some remnants of the Xiongnu from the northwest; and the Chiang people of Gansu and Tibet (present-day China's Xizang Autonomous Region) from the west and the southwest. Chaos prevailed as these groups warred with each other and repulsed the vain efforts of the fragmented Chinese kingdoms south of the Yangtze River to reconquer the region.
By the end of the 4th century, the region between the Yangtze and the Gobi, including much of modern Xinjiang, was dominated by the Toba. Emerging as the partially sinicized state of Dai between AD 338 and 376 in the Shanxi area, the Toba established control over the region as the Northern Wei Dynasty (AD 386-533). Northern Wei armies drove back the Ruruan (referred to as Ruanruan or Juan-Juan by Chinese chroniclers), a newly arising nomadic Mongol people in the steppes north of the Altai Mountains, and reconstructed the Great Wall. During the 4th century also, the Huns left the steppes north of the Aral Sea to invade Europe. By the middle of the 5th century, Northern Wei had penetrated into the Tarim Basin in Inner Asia, as had the Chinese in the 2nd century. As the empire grew, however, Toba tribal customs were supplanted by those of the Chinese, an evolution not accepted by all Toba.
The Ruruan, only temporarily repelled by Northern Wei, had driven the Xiongnu toward the Ural Mountains and the Caspian Sea and were making raids into China. In the late 5th century, the Ruruan established a powerful nomadic empire spreading generally farther north of Northern Wei. It was probably the Ruruan who first used the title khan.
Read more about this topic: Mongols Before Genghis Khan